"""
自定义分页面组件，需要做以下事情：

在视图函数中：
    def list(request):
        1. 根据筛选条件进行查询数据
        queryset = models.PrettyNum.objects.filter(**data_dict).order_by("-level")
        2. 实例化分页对象
        page_object = Pagination(request,queryset)

        context = {
            'data_list': page_object.page_queryset, # 分页后的数据
            "page_string": page_object.html  # 页码
        }
在html页面中：
    {% for obj in queryset %}
        {{obj.XX}}
    {% endfor %}

    <ul class="pagination">
        {{ page_string }}
    </ul>
"""


from django.utils.safestring import mark_safe
import copy


class Pagination():
    def __init__(self,request,queryset,page_size = 10,page_param="page",plus=5):
        """
        request    请求的对象
        queryset   符合条件的数据（根据这个数据进行分页处理）
        page_size  每页显示多少条数据
        page_param 在URL中传递的获取分页的参数，例如：?page=3
        plus       现实当前页的 前后几页（根据页码）
        """

        query_dict = copy.deepcopy(request.GET)
        query_dict._mutable = True
        self.query_dict = query_dict

        page = request.GET.get(page_param, "1")

        if page.isdecimal():
            page = int(page)
        else:
            page = 1
        self.page_size = page_size
        # 总页码
        total_count = queryset.count()
        total_page_count, div = divmod(total_count, self.page_size)
        if div:
            total_page_count += 1
        self.page_param = page_param
        self.page = page
        self.start = (page - 1)* page_size
        self.end = page * page_size
        self.page_queryset = queryset[self.start:self.end]
        self.total_page_count = total_page_count
        self.plus = plus


    def html(self):

        # 计算出 当前页面的前5页，后5页
        if self.total_page_count <= 2 * self.plus + 1:
            # 查询出的数据比较少，没有达到 plus * 2 + 1
            start_page = 1
            end_page = self.total_page_count
        else:
            # 查询出的数据比较多，超过 plus * 2 + 1
            if self.page <= self.plus:
                # 当前页 小于 plus
                start_page = 1
                end_page = 2 * self.plus + 1
            else:
                if (self.page + self.plus) > self.total_page_count:
                    # 当前页面 > plus
                    # 当前页面 + plus > 总页码
                    start_page = self.total_page_count -1 * self.plus + 2
                    end_page = self.total_page_count
                else:
                    start_page = self.page - self.plus
                    end_page = self.page + self.plus + 1


        # # 页码
        page_str_list = []
        self.query_dict.setlist(self.page_param, [1])

        # 首页
        if self.page != 1:
            page_str_list.append('<li><a href="?{}">首页</a></li>'.format(self.query_dict.urlencode()))

        # 上一页
        if self.page > 1:
            self.query_dict.setlist(self.page_param, [self.page - 1])
            page_str_list.append('<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode()))

        # 页面
        for i in range(start_page, end_page+1):
            self.query_dict.setlist(self.page_param, [i])
            if i == self.page:
                ele = '<li class="active"><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            else:
                ele = '<li><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            page_str_list.append(ele)


        # 下一页
        if self.page < self.total_page_count:
            self.query_dict.setlist(self.page_param, [self.page + 1])
            page_str_list.append('<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode()))

        # 尾页
        if self.page != self.total_page_count:
            self.query_dict.setlist(self.page_param, [self.total_page_count])
            page_str_list.append('<li><a href="?{}">尾页</a></li>'.format(self.query_dict.urlencode()))

        search_string = """                    
                            <li>
                                <form style="float: left;margin-left: -1px" method="get">
                                       <input style="position: relative;float:left;display: inline-block;width: 80px;border-radius: 0;" type="text" name="page" class="form-control" placeholder="页码">
                                        <button style="border-radius: 0;" class="btn btn-default" type="submit">跳转</button>
                                </form>
                            </li>
                            """
        page_str_list.append(search_string)
        page_string = mark_safe("".join(page_str_list))

        return page_string





















